Stevioside,commonly known as stevia and relatively new to the list of sugar substitutes,is used as a non-caloric sweetener in several countries. Native to South America,stevia is extracted from Stevia rebaudiana leaves. These plant leaves have been used as a sweetener since 1970s. Stevia is available as a dietary supplement in the United States,and has not been yet approved for use as a sweetener by US FDA (Food and Drug Administration,United States).
The leaf of the stevia plant contains certain compounds,most abundant being stevioside and rebaudioside A,that give it sweetness. These compounds are about 250-300 times sweeter than sugar but their metabolism in the body has not been completely investigated.
A number of studies have suggested that,besides sweetness,stevioside along with other compounds may also have anti-hyperglycemic (blood sugar lowering),anti-hypertensive (blood pressure lowering),anti-inflammatory,anti-tumour and immuno-modulatory actions. However,more research is needed to validate these benefits.
Stevia is considered a good substitute to regular table sugar as it is sweeter and has zero calorie. According to EFSA (European Food Safety Authority) panel on food additives and nutrient sources, the acceptable daily intake of stevia was determined at 4mg/kg body weight (measured as steviol equivalents),a level consistent with that already established by the Joint FAO/WHO Expert Committee on Food Additives (JECFA). This intake is set with a wide margin of safety and no adverse effects have been seen in intakes of stevia 100 times greater than the acceptable daily intake.
FDA has not actually declared stevia as a sugar substitute but rather only certain highly refined stevia preparations that contain rebaudioside A as generally recognised as safe (GRAS),which means that they can be used as sugar substitutes.
In general,products marketed as stevia are whole leaf stevia or stevia extracts of which Rebaudioside A is a component. These highly refined stevia extracts may cause mild side-effects such as nausea or a feeling of fullness in some individuals.
FDA has not permitted the use of whole-leaf stevia or crude stevia extracts as food additives because of concerns about potential health effects. Among these concerns are the effects of stevia on blood sugar control,kidneys,cardiovascular and reproductive systems.
Remember that the daily allowance of sugar substitutes such as refined stevia preparations may be way above our intake,yet a prudent approach is desirable.